1. Field of the Invention
The invention described herein relates to computer-aided design (CAD) and to fabrication.
2. Related Art
Computer aided design (CAD) is now widely used in a variety of industries. For example, CAD technology is used by the electronics industry to design chips, by the automotive industry to design mechanical components, and by architects to render building designs. The popularity of CAD is due in part to its ability to facilitate rapid and economical design. Moreover, in many CAD applications, the resulting design can be easily saved and converted into a final product. The fabrication of circuit boards is an example of this.
In other fields, however, the conversion of a computer-aided design to a final product is less practical. In particular, the fabrication of large three-dimensional solids that have been designed with a CAD process can be difficult. Existing fabrication methods, such as stereo lithography and laser sintering, are capable of precisely constructing three-dimensional solids directly from a CAD process, but the capabilities of these fabrication methods are limited. Such fabrication processes generally build a solid using an iterative layering process. Such processes can operate, for example, by using heat to solidify successive layers of resin at points determined by the CAD process. This results in the desired three-dimensional solid. Such processes may alternatively build an object by successively layering particulate matter, such as metal shavings, and bonding the particles at locations determined by the CAD process. These processes are limited, however, in the size of the solid that can be built. While they can generally produce an arbitrary three-dimensional shape, they are not typically able to build an object larger than a two foot cube. Moreover, these methods are slow. Construction of a two foot cube can take 24 hours. These processes are also expensive, and the equipment tends to be difficult to maintain. In general, these processes are more useful for construction of models, i.e., prototyping, rather than for production of full-scale objects.
There is a need, therefore, for a method by which large three-dimensional objects can be designed using a CAD process, such that the resulting design lends itself to ready fabrication. Fabrication based on such a design must be relatively fast and inexpensive.
The invention described herein is a method, system, and computer program product for the design and fabrication of an object comprised of one or more surfaces. A process begins by using a CAD process to design surfaces of the object. In particular, the surfaces are modeled using developable surfaces only. The intersections of the developable surfaces are then calculated. Any excess surface area of the developable surfaces is trimmed. The boundaries of each developable surface are abstracted to produce a two-dimensional planar model of each developable surface. From each planar model, a full-sized two-dimensional shape can then be fabricated in proportion to the planar model. Each fabricated shape can then be bent in accordance with the corresponding developable surface of the CAD model. Finally, the edges of the fabricated shapes are attached as determined by the calculated intersections of the developable surfaces.
Features and Advantages
The invention has the feature of allowing the computer-aided design of arbitrarily large surfaces and shapes. The invention has the additional feature of using developable surfaces to model the surfaces of an object.
The invention has the advantage of modeling the surfaces of an object so that the ultimate fabrication of the surfaces can be done precisely. The invention has the further advantage of providing a means for ready attachment of the edges of fabricated shapes.